1. Field of the Invention
The present invention relates to an optical amplifying system and a method of controlling the optical amplifying system.
2. Background Arts
An optical amplifying system that optically amplifies light coming from a semiconductor laser diode (LD) has been well known in the field. A Japanese Patent laid open No. JP-H10-209542A has disclosed an optical amplifying system that shows a large optical gain by entering a pulsed optical signal with a width substantially equal to a rising time of the semiconductor optical amplifier (SOA). Another technique regarding an SOA has been disclosed in a Japanese Patent laid open No. JP2013-149949A, where an SOA shows an optical output signal with smaller distortion by biasing an SOA in a region where optical power output from an SOA decreases as increasing the bias. Still another Japanese Patent application laid open No. JP2010-239051A has disclosed that an optical device, which integrates an LD with an optical modulator on a semiconductor substrate common to the LD and the optical modulator and the LD in an active layer and the optical modulator in an optical absorbing layer are coupled with an optical waveguide with a width smaller than 1.35 μm, may suppress modes of higher degrees.